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Rainfall-induced landslides are a significant hazard in areas covered by granite residual soil in northern Guangdong Province. To study the response of granite residual soil landslides to rainfall, the most severely affected area during the floods in June 2022 and April 2024 was chosen as the study area. Geological investigations and field artificial rainfall tests were conducted to explore the deformation evolution characteristics of granite residual soil slopes under continuous heavy rainfall and to reveal the failure mechanism of rainfall-induced landsliding events. The results indicate that the granite residual soil can be divided into two layers, and the slope structure can be subdivided into three models from the geological point of view. Given that the deformation and failure characteristics of the surficial landslides are highly similar across the three models, the three models can be consolidated into a single model composed of granite residual soil and weathered granite. The intensity and persistence of rainfall are the main triggering factors of landslides in this area. The landslides are primarily characterized by surficial sliding with a traction sliding failure mode, mainly involving a granite residual soil layer thickness of about 1–3 m. The increased rate of water content and the range of pore water pressure can be used as primary indicators for slope deformation and failure. Additionally, shear dilatancy deformation during slope movement effectively mitigates deformation rates. Furthermore, debris flow is identified as a secondary disaster resulting from landslides, with landslide deposits serving as potential sources for debris flow.

A quantitative assessment of the seismic stability of anchored anti-dip slopes is of great importance for the safety of residents and infrastructure in seismically active regions. However, the subject has received relatively little scientific attention globally. This study aims to analyze the dynamic stability of an anchored anti-dip slope during the Ludian earthquake in Yunnan Province, China, a region characterized by active faults and frequent strong earthquakes. The Manhekuan slope located near the Lancang River fault, an active fault in Yunnan Province, was chosen as a case study to propose a method that integrates engineering geological investigations with the discrete element method (DEM). To validate its effectiveness, the proposed method is compared with the pseudo-static method and subsequently applied to optimize the anchorage parameters of the Manhekuan slope. The results indicate that the stability factor achieved by the proposed method is slightly higher than that of the pseudo-static method, showing a 3.6% increase. The proposed method effectively describes the shear evolution characteristics of the anchor cable and its influence on the seismic dynamic stability of the anchored anti-dip slope. The dynamic stability of the Manhekuan slope under the Ludian earthquake is reasonably analyzed using three indices: stability factor, geological body displacement, and anchorage force. This analysis leads to the determination of optimal anchorage parameters for the Manhekuan slope. The findings provide a valuable reference for evaluating the seismic stability of anchored slope engineering in seismically active regions, including the Himalayas.

Identifying factors and quantifying the processes, influencing the extent of reservoir rocks and the distribution of their heterogeneities are fundamental prerequisites to improve the characterization of reservoir connectivity and its dynamic functioning. In this paper, we propose a multiscale approach based on combined geological–geophysical investigations, geostatistics, and 3D geological modeling to build a structural model of faulted-reservoir systems, at regional and local scales within the Jeffara basin, southeast Tunisia. The regional modeling procedure is calibrated by outcrops, a Digital Elevation Model (DEM), boreholes, and well data logs. The geological processing, itself, is used as a tool to extend the database from a variety of documents such as geological maps, geological cross-sections, outcrop descriptions, and especially the wealthy geological knowledge. The original and extended data are then coded and stored in a common georeferenced database. This provides a detailed input for the geostatistical modeling procedures that enabled to precisely capture the varying extent and shape of the hydrogeological units at regional scale. Geophysical data, available along the Jeffara plain, were added as a complement to the Jeffara geodatabase and used to establish the fault network and to build a local architectural model of the coastal aquifer system, based on time-to-depth conversion using kriging with external drift. The results have allowed (i) a major update of the geological configuration of the Jeffara basin, (ii) more precision on the geometries and extent of the stratigraphic sequences and (iii) an accurate prediction of the main characteristics of water reservoirs, i.e. their occurrence, thickness, facies and dynamic properties variation at the basin and reservoir scale. Such multiscale modeling provided effective tools for better understanding the hydrostratigraphic setting, the hydrodynamic functioning of neighboring aquifers, and to assist water resources management.

The Daguangbao landslide is the largest co-seismic landslide triggered by the Wenchuan earthquake (Ms 8.0) occurred on 12 May 2008. The landslide, which is 4.6 km long and 3.7 km wide, involves a volume of approximately 1.2 × 109 m3. An exposed slip surface, situated at the southern flank of its source area, was observed with a length of 1.8 km along the main sliding direction and an area of 0.3 km2. To study the geological and tectonic characteristics of the source area and their contributions to the landslide formation during the earthquake, detailed geological investigations were firstly conducted. And it is reached that the landslide occurred on the northwestern limb of the Dashuizha anticline with its scarp showing several geological structures, including joint sets, local faults, and folds. These tectonic-related structures potentially influenced the failure of the landslide. Secondly, further investigations were focused on the inclined planar sliding surface using 12 exploratory trenches, nine boreholes, a tunnel, borehole sonic data, and micro-images. These data reveal that the rock mass along the sliding surface was the fragmented rock of a bedding fault. A pulverized zone was observed on the sliding surface, which was the zone of shear localization during the landslide. This suggests that the shear failure of the Daguangbao landslide developed within the bedding fault. The rapid failure of the landslide was associated with the degradation of the rock mass strength of the bedding fault both before and during the 2008 Wenchuan earthquake. With this study, we propose that a pre-existing large discontinuity within a slope may be the basis for initiating a large landslide during earthquake.

Geological investigations planned for the Europa Clipper mission will examine the formation, evolution, and expression of geomorphic structures found on the surface. Understanding geologic features, their formation, and any recent activity are key inputs in constraining Europa’s potential for habitability. In addition to providing information about the moon’s habitability, the geologic study of Europa is compelling in and of itself. Here we provide a high-level, cross-instrument, and cross-discipline overview of the geologic investigations planned within the Europa Clipper mission. Europa’s fascinating collection of ice-focused geology provides an unparalleled opportunity to investigate the dynamics of icy shells, ice-ocean exchange processes, and global-scale tectonic and tidal stresses. We present an overview of what is currently known about the geology of Europa, from global to local scales, highlighting outstanding issues and open questions, and detailing how the Europa Clipper mission will address them. We describe the mission’s strategy for searching for and characterizing current activity in the form of possible active plumes, thermal anomalies, evidence for surface changes, and extremely fresh surface exposures. The complementary and synergistic nature of the data sets from the various instruments and their integration will be key to significantly advancing our understanding of Europa’s geology.

Continuous use of diversion-based irrigation has been associated with an increase in the frequency of loess landslides on the South Jingyang Platform, Shaanxi, China. A loess landslide event with a maximum sliding distance of 278 m occurred near the village of Miaodian on May 26, 2015. This landslide event was characterized by four individual landslides. Field investigations, geological exploration, numerical simulation, isotropically consolidated undrained (ICU) triaxial tests, and ring shear tests were conducted to identify its initiation and movement mechanisms. The ICU tests revealed that saturated loess samples were highly liquefiable. High pore water pressure was quickly produced and deviation stress increased the highest value even at low values of axial strain. Geological investigations revealed that cracks penetrated into the saturated zone from the ground surface, and simulation results revealed that these cracks played a dominant role in the infiltration of surface water and led to a rise in the groundwater table. When the infiltration recharge exceeds the holding capacity of the paleosol, the latter behaves as aquifuge under relatively undrained conditions. This process results in the accumulation of water at the bottom of the loess layer, thereby contributing to soil liquefaction and landslide initiation. The ring shear tests revealed that the saturated sand layer of the landslide substrates was subjected to easily inducible high pore water pressure under undrained conditions which led to the thrusting of the sand layer onto the deposit surface and explains the high speed and long runout distance of this landslide.

Borehole data are essential for conducting precise urban geological surveys and large-scale geological investigations. Traditionally, explicit modelling and implicit modelling have been the primary methods for visualizing borehole data and constructing 3D geological models. However, explicit modelling requires substantial manual labour, while implicit modelling faces problems related to uncertainty analysis. Recently, machine learning approaches have emerged as effective solutions for addressing these issues in 3D geological modelling. Nevertheless, the use of machine learning methods for constructing 3D geological models is often limited by insufficient training data. In this paper, we propose the semi-supervised deep learning using pseudo-labels (SDLP) algorithm to overcome the issue of insufficient training data. Specifically, we construct the pseudo-labels in the training dataset using the triangular irregular network (TIN) method. A 3D geological model is constructed using borehole data obtained from a real building engineering project in Shenyang, Liaoning Province, NE China. Then, we compare the results of the 3D geological model constructed based on SDLP with those constructed by a support vector machine (SVM) method and an implicit Hermite radial basis function (HRBF) modelling method. Compared to the 3D geological models constructed using the HRBF algorithm and the SVM algorithm, the 3D geological model constructed based on the SDLP algorithm better conforms to the sedimentation patterns of the region. The findings demonstrate that our proposed method effectively resolves the issues of insufficient training data when using machine learning methods and the inability to perform uncertainty analysis when using the implicit method. In conclusion, the semi-supervised deep learning method with pseudo-labelling proposed in this paper provides a solution for 3D geological modelling in engineering project areas with borehole data.

This study evaluates the efficiency of some open source optical remote sensing data (Landsat OLI, Sentinel-2 A, ASTER and DEM) in automatic lineaments extraction over Lokoja region of Central Nigeria. Various image processing techniques involving principal component analysis (PCA), directional filtering and shaded relief were employed followed by a robust lineament extraction technique and novel false lineaments filtration method. The result indicated significant variation in the number, length and accuracy of extracted lineaments across the datasets. Comparison of results by way of accuracy assessment was achieved after superimposition of extracted lineaments on geological map and shading map of the study area as well as by comparing their orientations with field obtained fracture data. Landsat OLI and Sentinel-2 A demonstrated better performance by extracting longer and more numerous lineaments many of which correlated with lithological boundaries and boundaries between shaded and unshaded areas. Orientations of the extracted lineaments indicated a majorly ENE-WSW and NE-SW trend while the field obtained fracture orientations showed a majorly NNW-SSE and NE-SW directions. All the images failed to identify lineaments along the NW-SE directions. The findings of this study underscored the importance of selecting appropriate datasets for regional geological investigations.

A comprehensive field investigation and analysis of the spatial distribution of landslides was conducted in the Three Gorges Reservoir Area (TGRA) along the Yangtze River and its first-order tributaries. A landslide inventory for this area was prepared using regional-local geological investigations and other available information. The analysis of the extensive inventory data reveals that the occurrence of landslides is mainly affected by four primary factors: (1) Lithology—the highest incidence of landslides is associated with the lithological combination of marl and shale intercalated with mudstone (MSM), and a number of landslides occurred in an area dominated by sandstone and mudstone intercalated with shale and coal seams (SMSC), which cover a major part (approximately 71%) of the bank slopes; (2) Structure—slope structure fundamentally controls the development of the sliding zone and the mechanism of formation of landslides occurring on the same lithological combinations at subregional scales. Landslide concentrations in consequent slopes are approximately 5–17 times greater than those of reverse slopes and diagonal slopes; (3) Topography—landslides are particularly abundant between elevations of 100 m and 600 m. The elevations of the headscarps of the landslides gradually decrease from the head to the tail of the reservoir due to the topography, and almost all of the toes of the landslides are below the highest historical floodwater level. The analysis of the correlation between landslide occurrence and hillslope gradients shows that 50% of all landslides occurred on slopes between 10° and 15°, despite slopes in this range representing only 30% of the total hillslope gradients; and (4) Water level fluctuation and precipitation—the fluctuation of reservoir water level exerts a fundamental effect that controls the occurrence and reactivation of landslides during the period of initial impoundment, whereas the precipitation becomes even more important than water level fluctuation after the first impoundment at 175 m above sea level. In addition, the comprehensive analysis performed in this study provides broad insight into the landslide distribution in the TGRA. This work will improve our understanding of the role of morphological and geological conditions that affect the occurrence of landslides, which may provide useful guidance for regional risk assessment and landslide susceptibility studies.

Archean rock exposures in the Yangtze Craton of South China are scarce and have been only studied in small-scale outcrops for understanding its early crustal evolution. Geological investigations have been carried out for three Neoarchean gneissic granitic plutons from the Dabie orogen in the northeastern margin of the Yangtze Craton. Zircon U-Pb geochronology constrains the emplacement of high-K monzogranite at 2645±30 Ma, high-K syenogranite at 2630±37 Ma and Na-rich granodiorite at 2497±29 Ma. These findings provide direct evidence for the existence of ∼2.7–2.5 Ga rocks in the Dabie orogen, which significantly contribute to the distribution and evolution of Neoarchean basement rocks in the Yangtze Craton. Zircon crystals from the three granite samples give ε Hf ( t ) values of −0.9 to 3.7, −4.2 to −0.4 and −4.7 to 0.1, respectively, corresponding to T DM2 ages of 3186–2909, 3372–3141 and 3297–3005 Ma. The magmatic zircons have δ 18 O values of 5.06±0.27‰ to 5.79 ±0.30‰ (average 5.59‰), 6.14±0.24 to 7.35±0.26‰ (average 6.87‰) and 5.95±0.17‰ to 7.09±0.17‰ (average 6.55‰), respectively. Considering the possible decrease of δ 18 O value due to the lead loss during post-crystallization alteration, the primary δ 18 O values might be substantially higher than those of the normal mantle zircon value ( δ 18 O=5.3±0.6‰). These isotopic data indicate that the Jiamiao Neoarchean granites were largely generated through reworking of Paleo-Mesoarchean basement rocks with a minor contribution of supracrustal material. Integrating our findings with previous results, we infer that the Archean-Paleoproterozoic complexes/terranes of the Yangtze Craton have distinct petrogenesis and the timings of the transition from Na-rich to high-K granites, crustal growth, and tectonothermal evolution before ∼2.0 Ga. However, all of them underwent metamorphism at about 2.0 Ga. These observations also reveal that the Yangtze Craton might comprise several microcontinents that evolved individually and collided to form a unified craton at ∼2.0 Ga, synchronous with the assembly of the Columbia supercontinent. However, the lack of relevant data from the southeastern Yangtze Craton may have a critical influence on this conclusion and should be solved in the future.